MUTHAYAMMAL ENGINEERING COLLEGE
(An Autonomous Institution)
(Approved by AICTE, New Delhi, Accredited by NAAC & Affiliated to Anna University)
Rasipuram - 637 408, Namakkal Dist., Tamil Nadu.
MUST KNOW CONCEPTS
MKC
ECE
2021-22
Course Code & Course Name
:
19ECC01& ELECTRIC NETWORK ANALYSIS AND MACHINES
Year/Sem/Sec : II/III/A,B,C
S.No.
Term
Notation
(Symbol)
Concept / Definition / Meaning /
Units / Equation / Expression
Units
Unit-I : THEOREMS AND DC TRANSIENT ANALYSIS
1.
Kirchhoff's
current law
-
Kirchhoff's current law says the currents
flowing into a node must add up to zero.
-
2.
Kirchhoff’s
voltage law
-
The algebraic sum of all voltages within the
loop must be equal to zero.
-
3.
Ohm’s law
R=V/I
The current through conductor between two
points is directly proportional to
the voltage across the two points.
Ohms
4.
Nodal analysis
-
It is using the nodal equations of Kirchhoff’s
first law to find the voltage potentials around
the circuit.
-
5.
Mesh analysis
-
It is used to find the currents circulating
around a loop or mesh with in any closed path
of a circuit.
-
6.
Superposition
theorem
-
In any linear, active, bilateral network having
more than one source, the response across any
element is the sum of the responses obtained
from each source considered separately and
all other sources are replaced by their internal
resistance.
-
7.
Thevenin's
Theorem
-
Any linear circuit containing several voltages
and resistances can be replaced by just one
single voltage in series with a single resistance
connected across the load.
-
8.
Norton’s Theorem
-
Any linear circuit containing several energy
sources and resistances can be replaced by a
-
single Constant Current generator in parallel
with a Single Resistor.
9.
Maximum power
transfer theorem
-
The maximum amount of power will be
dissipated in the load resistance if it is equal in
value to the Thevenin or Norton source
resistance of the network supplying the
power.
-
10.
Reciprocity
theorem
-
The deflection at point 1 in a given direction
due to a unit load at point 2 in a second
direction is equal to the deflection at point 2 in
the second direction due to a unit load at point
1 in the first direction.
-
11.
Tellegen's
Theorem
-
Tellegen's Theorem states that, the summation
of power delivered is zero for each branch of
any electrical network at any instant of time.
-
12.
Compensation
Theorem
-
Any resistance in a network may be replaced
by a voltage source that has zero internal
resistance and a voltage equal to the voltage
drop across the replace resistance due to the
current which was flowing through it.
-
13.
Millman's
theorem
-
Millman's theorem is used to compute the
voltage at the ends of a circuit made up of
only branches in parallel.
-
14.
RC circuit
-
It is an electric circuit composed of resistors
and capacitors driven by a voltage or current
source.
-
15.
RL circuit
-
It is an electric circuit composed of resistors
and inductors driven by a voltage or current
source.
-
16.
source-free RC
circuit
-
A source-free RC circuit occurs when its
DC source is suddenly disconnected. The
energy already stored in the capacitor is
released to the resistor & dissipated. This is a
first-order differential equation.
-
17.
source-free RL
circuit
-
A source-free circuit is where all
independent sources have been disconnected
-
from the circuit after some switch action. The
voltages and currents in the circuit typically
will have some transient response due to
initial conditions
18.
Step function
-
A function on the real numbers is called
a step function (or staircase function) if it can
be written as a finite linear combination of
indicator functions of intervals.
-
19.
Forced response
-
The forced response is what the circuit does
with the sources turned on but with the initial
conditions set to zero.
-
20.
Natural response
-
The natural response is what the circuit does
including the initial conditions, but with the
input suppressed.
-
21.
Damped circuit
-
An RLC circuit is an
electrical circuit consisting of a resistor (R), an
inductor (L), and a capacitor (C), connected in
series or in parallel.
-
22.
Underdamped
circuit
-
An underdamped response is one that
oscillates within a decaying envelope.
-
23.
Open circuit
-
An open circuit implies that the two terminals
are points are externally disconnected, which
is equivalent to a resistance R=∞ .
-
24.
Shot circuit
-
This means that zero current can flow between
the two terminals, regardless of any voltage
difference.
-
25.
RLC circuit
-
RLC circuit is an electrical circuit consisting of
a resistor (R), an inductor (L), and a capacitor
(C), connected in series or in parallel.
-
Unit-II : SINUSOIDAL AND STEADY STATE POWER ANALYSIS
26.
Steady sate
-
A steady-state is an unchanging condition,
system or physical process that remains the
same even after transformation or change.
-
27.
Active component
-
An active component is an
electronic component which supplies energy
to a circuit.
-
28.
Passive
component
-
A passive element is an
electrical component that does not generate
power, but instead dissipates, stores, and/or
releases it.
-
29.
Impedance
Z
The measure of the opposition of an electric
current to the energy flow when voltage is
applied.
-
30.
Admittance
Y
Admittance is the reciprocal of impedance, Z
and is given the symbol Y.
-
31.
Network theorem
-
The current through, or voltage across, any
element of a network is equal to the algebraic
sum of the currents or voltages produced
independently by each source.
-
32.
RMS value
-
The RMS value is the effective value of a
varying voltage or current. It is the equivalent
steady DC (constant) value which gives the
same effect.
-
33.
Power
-
The source of energy used to operate a
machine or other system.
-
34.
Power factor
-
Power factor is defined as the ratio of
real power (P) to apparent power (S),
-
35.
Magnetically
coupled circuit
-
Magnetically coupled circuit means that two
loops, with or without contacts between them,
affect each other through the magnetic field
generated by one of them.
-
36.
Self inductance
-
Self-inductance of the coil is defined as the
property of the coil due to which it opposes
the change of current flowing through it.
-
37.
Mutual
Inductance
-
Mutual Inductance is the interaction of one
coil magnetic field on another coil as it induces
a voltage in the adjacent coil.
-
38.
Minimum
function
-
If degrees of numerator and denominator
were unequal, a pole or zero can be removed.
Such a function cannot be a minimum
function.
-
39.
Phasor
-
Phasors are vector representation of sinusoidal
signals. Phasors suppress the element of time.
-
The length of the phasor or its magnitude is
the amplitude or maximum value of the cosine
function.
40.
Coupled circuits
-
Coupled circuits is the form of multi-turn coils
sharing a magnetic circuit, where the magnetic
flux produced by the current in one coil not
only links with its own winding, but also with
those of the other coils.
-
41.
Forced response
-
Forced response is the system's response to an
external stimulus with zero initial conditions.
-
42.
sinusoidal
function
-
A sinusoidal function is a function that is like
a sine function in the sense that
the function can be produced by shifting,
stretching or compressing the sine function.
-
43.
Steady state
analysis
-
In the steady state, the charge (or current)
flowing into any point in the circuit has to
equal the charge (or current) flowing out.
-
44.
Parallel resonance
-
In a parallel resonant circuit, the circuit
current at resonance is maximum.
-
45.
Response
-
The current flowing through or voltage across
branches in the circuit is called response.
-
46.
Transient response
-
The voltage or current are changed from one
transient state to another transient state is
called transient response.
-
47.
Natural response
-
The response determined by the internal
energy stored in the network is called natural
response.
-
48.
Transient
-
The state (or condition) of the circuit from the
transient of switching to attainment of steady
state is called transient state or simply
transient.
-
49.
Critical resistance
-
The critical resistance is the value of the
resistance of the circuit to achieve critical
damping.
-
50.
Time constant of
RL circuit
-
The time constant of RL circuit is defined as
the ratio of inductance and resistance of
the circuit.
-
Unit-III : APPLICATION OF LAPLACE TRANSFORM TO CIRCUIT ANALYSIS
51.
Complex
frequency.
-
A type of frequency that depends on two
parameters, one is the σ which controls the
magnitude of the signal and the other is w,
which controls the rotation of the signal is
known as “complex frequency”.
-
52.
Laplace transform
-
Laplace transform is the integral transform of
the given derivative function with real
variable t to convert into complex function
with variable s.
-
53.
Significant of
Laplace transform
The Laplace transform is used for solving
linear differential and integral equations.
54.
Uses of Laplace
transform
-
It is used for analysis of linear time-invariant
systems such as electrical circuits, harmonic
oscillators, optical devices, and mechanical
systems.
-
55.
Inverse Laplace
transform
-
A Laplace transform which is a constant
multiplied by a function has an inverse of the
constant multiplied by the inverse of the
function.
-
56.
Properties of
Laplace transform
-
1. Linearity Property.2. Time Shifting Property
3. Frequency Shifting Property 4. Time
Reversal Property.5. Time Scaling Property.
-
57.
Damped sinusoid
-
Damped sinusoid is a sinusoidal
function whose amplitude approaches zero as
time increases.
-
58.
Frequency
domain
-
Frequency-domain analysis is widely used in
such areas as communications, geology,
remote sensing, and image processing.
-
59.
Time-domain
-
A time-domain graph shows how a signal
changes over time
-
60.
Frequency
-
Frequency is the number of occurrences of a
repeating event per unit of time.
-
61.
the time-domain
relation between
the current in
inductance
-
-
62.
the time-domain
relation between
the voltage VL(t)
in inductance
-
-
63.
For capacitance,
the time-domain
relation between
voltage
-
-
64.
For capacitance,
the time-domain
relation between
current
-
-
65.
root of the
characteristic
equation
-
-
66.
A Resistor in the s-
Domain
-
-
67.
An Inductor in the
s-Domain
-
-
68.
A Capacitor in the
s-domain
-
-
69.
Transfer
Admittance
-
It is defined as the ratio of current transform at
one port to the voltage transform
at the other port, and is denoted by Y(s).
-
70.
Transfer
Impedance
-
It is defined as the ratio of voltage transform
at one port to the current transform
at the other port, and is denoted by Z(s).
-
71.
Current-Transfer
Ratio
-
This is the ratio of current transform at one
port to current transform at
other port, and is denoted by a(s).
-
72.
Voltage transfer
Ratio
-
-
73.
Driving Point
Admittance
-
-
74.
Driving Point
Impedance
-
-
75.
Significance of
poles and zeros
-
Poles and zeros are critical frequencies. At
poles, the network function become infinite,
while at zeros, the
network function becomes zero
-
Unit-IV : NETWORK TOPOLOGY AND TWO PORT NETWORK
76.
Branch
-
A branch is represented by a line segment
connecting a pair of nodes in the graph
of a network.
-
77.
Node
-
A node is a terminal of a branch, which is
represented by a
point. Nodes are the end points of branches.
-
78.
Directed graph
-
If every branch of a graph has a direction
-
79.
Planar graph
-
A graph is said to be planar if it can be drawn
on a plane surface such that no two branches
cross each other
-
80.
Non-planar graph
-
There will be branches which are not in the
same plane as others, i.e. a non-planar
graph cannot be drawn on a plane surface
without a crossover
-
81.
Tree
-
A tree is a connected subgraph of a network
which consists of all the nodes of the
original graph but no closed paths.
-
82.
Co-Tree
-
The set of all links of a given tree is called
-
the co-tree of the graph.
83.
Links
-
In forming a tree for a given graph, certain
branches are removed or opened.
The branches thus opened are called links
-
84.
Twigs
-
The branches of a tree are called its twigs
-
85.
Rank of the tree
-
The number of twigs (n – 1) is known as the
tree value of the graph. It is also called the
rank of the tree
-
86.
Loop
-
If a link is added to the tree, the resulting
graph contains one closed path, called a loop.
-
87.
Incidence matrix
-
The incidence of elements to nodes in a
connected graph is shown
by the element node incidence matrix
-
88.
Tie-set
-
The fundamental loop formed by one link has
a unique path in the tree joining the two nodes
of the link. This loop is also called f-loop or a
tie-set
-
89.
A cut-set
-
A cut-set is a minimal set of branches of a
connected graph such that the removal
of these branches causes the graph to be cut
into exactly two parts
-
90.
Port
-
A pair of terminals at which a signal may
enter or leave a network is called a port.
-
91.
Two-port network
-
A two-port network is simply a network
inside a black box, and the network has only
two pairs of accessible terminals; usually one
pair represents input and the other represents
the output.
-
92.
Z-Parameters
-
Z-parameters of a two‑port for the positive
directions of voltages and currents may be
defined by expressing the port voltages V1
and V2 in terms of
the currents I1 and I2
-
93.
Open‑circuit
output impedance
-
-
94.
Y-parameters
-
The Y-parameters of a two‑port network for
the positive directions of voltages and currents
may be defined
by expressing the port currents I1 and I2 in
terms of the voltages V1 and V2.
-
95.
Short‑circuit input
admittance.
-
-
96.
Short‑circuited
forward transfer
admittance
-
-
97.
Short‑circuit
reverse transfer
admittance
-
-
98.
Transmission
parameters
-
-
99.
Quality factor
-
-
100.
Resonant
frequency
-
The frequency at which
the resonance occurs is called the resonant
frequency
-
Unit-V : ELECTRIC MACHINES
101.
Three basic
rotating machines
types
-
1.The dc machines
2.the poly phase synchronous machine (ac),
and
3. Poly and single phase induction machine
(ac)
-
102.
Leakage flux
-
The flux setup in the air paths around the
magnetic material is known as leakage flux.
-
103.
Fringing
-
In the air gap the magnetic flux fringes out
into neighboring air paths due to the
reluctance of air gap which causes a non
uniform flux density in the air gap of a
machine. This effect is called fringing effect.
-
104.
Magnetic
materials
-
Alnicos, chromium steels, copper–nickel alloy,
nickel, cobalt, tungsten and aluminum.
-
105.
Statically induced
emf
-
The coil remains stationary with respect to
flux, but the flux through it changes with time.
The emf induced is known as statically
induced emf.
-
106.
Dynamically
induced emf
-
Flux density distribution remains constant and
stationary but the coil moves relative to it. The
emf induced is known as dynamically induced
emf
-
107.
Fleming’s right
hand rule.
-
If the thumb represents the direction of
movement of conductor and the fore finger the
direction of magnetic flux, then the middle
finger represents the direction of emf
-
108.
Fleming’s Left
hand rule
-
If the forefinger represents the direction of
flux and the middle finger the direction of
current, then the middle finger represents the
direction of movement of conductor.
-
109.
Type of losses
-
Hysteresis loss, core loss and eddy current
loss.
-
110.
Applications of
DC series motor
-
Electric traction, Mixes Hoists, Drilling
machines
-
111.
Different types of
starters
-
1. Three-point starter
2. Four-point starter.
-
112.
Protective devices
in a starter
-
1, No volt release
2. Overload Release.
-
113.
Various torque
operations
-
1. DC series motor
2. DC cumulatively compound motor
-
114.
Speed regulation.
-
% Speed regulation= (NL speed- FL speed)
X100/ FL speed
-
115.
Performance
curves
-
Output Vs torque, Output Vs current, Output
Vs speed, Output Vs efficiency.
-
116.
Applications of
speed.
-
Used where regulated speed control is
required in applications such as metering
pumps and industrial process equipment.
-
117.
Alternators
classified
-
According to type of field system
Stationary field system type
Rotating field system type According to
shape of field system
Salient pole type
Smooth cylindrical type
-
118.
Types of
Alternator
-
Smooth cylindrical type alternator
Salient pole alternator
-
119.
Formula for
distribution factor
-
m=number of slots/ pole/ phase n = order of
harmonic
-
120.
Winding factor
-
The winding factor Kd is defined as the ratio
of phasor addition of emf induced in all the
coils belonging to each phase winding to their
arithmetic addition.
-
121.
Armature reaction
in Alternators
-
The interaction between flux set up by the
current carrying armature and the main is
defined as the armature reaction
-
122.
Voltage regulation
of an Alternator
by MMF method
-
Effective resistance per phase of the 3-phase
winding R
Open circuit characteristic (OCC) at rated
-
speed/frequency
Short circuit characteristic (SCC) at rated
speed/frequency
123.
Characteristic
features of
synchronous
motor
-
1. the motor is not inherently self-starting
2. The speed of operation is always in
synchronous with the supply frequency
irrespective of load conditions
3. The motor is capable of operating at any
power factor.
-
124.
Synchronous
motor
-
Synchronous motor operates due to magnetic
locking taking place between stator and rotor
magnetic fields
-
125.
Starting of
Synchronous
motor
-
By an extra 3 phase cage induction motor
By providing damper winding in pole
phases
By operating the pilot excitor as a dc motor
-
Placement Questions
126.
Current divider
rule
-
Current divider rule provides a useful real
relationship for determine the current through
individual circuit elements that are connected
in parallel
-
127.
Ideal voltage
source
-
A device with zero internal resistance.
-
128.
Ideal current
source
-
A device with infinite internal resistance.
-
129.
Practical voltage
source
-
A device with small internal resistance.
-
130.
Practical current
source
-
A device with large internal resistance.
-
131.
Voltage divider
rule
-
Voltage divider rule provides a useful formula
to determine the voltage across any resistor
when two or more resistors are connected in
series with a voltage source
-
132.
Circuit
-
The path between two points along which an
electrical current can be carried is called circuit
-
133.
Current
-
Current can be defined as the motion of
charge through a conducting material.
Ampere
134.
Inductor
-
An inductor is a passive electrical device
employed in electrical circuits for its property
of inductance.
-
135.
Capacitor
-
A capacitor is an electrical device that can
store energy in electric fields between a pair of
conductors
-
136.
Super node
-
A super node exists when an ideal voltage
source appears between any two nodes of an
electric circuit.
-
137.
Corkscrew rule
-
A current flow a wire, the magnetic field
rotates in the direction of a corkscrew
-
138.
Transient
-
The state (or condition) of the circuit from the
transient of switching to attainment of steady
state is called transient state or simply
transient.
-
139.
Critical damping
-
The critical damping is the condition of the
circuit at which the oscillations in the response
are just eliminated. This is possible by
increasing the value of resistance in the circuit.
-
140.
Damping ratio
-
The ratio of resistance of the circuit and
resistance for critical damping is called
damping ratio.
-
141.
Train problem
-
A train running at the speed of 60 km/hr
crosses a pole in 9 seconds. What is the length
of the train?
A)120 meters
B)180 meters
C)324 meters
D)150 meters
Ans: D)150 meters
-
142.
Time and work
-
A can do a work in 15 days and B in 20 days. If
they work on it together for 4 days, then the
fraction of the work that is left is :
Ans: 8/15
-
143.
Probability
-
Tickets numbered 1 to 20 are mixed up and
then a ticket is drawn at random. What is the
probability that the ticket drawn has a number
which is a multiple of 3 or 5?
Ans: 9/20
-
144.
Boat and stream
-
A boat can travel with a speed of 13 km/hr in
still water. If the speed of the stream is 4
km/hr, find the time taken by the boat to go
68 km downstream.
Ans: 4hours
-
145.
Simple interest
-
A sum of money at simple interest amounts to
Rs. 815 in 3 years and to Rs. 854 in 4 years. The
sum is:
Ans: Rs.698
-
146.
Ratio and
proportions
-
A and B together have Rs. 1210. If of A's
amount is equal to of B's amount, how
much amount does B have?
Ans: Rs.484
-
147.
Profit and loss
-
Alfred buys an old scooter for Rs. 4700 and
spends Rs. 800 on its repairs. If he sells the
scooter for Rs. 5800, his gain percent is:
Ans: 5(5/11) %
-
148.
Height and
distance
-
Two ships are sailing in the sea on the two
sides of a lighthouse. The angle of elevation of
the top of the lighthouse is observed from the
ships are 30° and 45° respectively. If the
lighthouse is 100 m high, the distance between
the two ships is:
Ans: 273m
-
149.
Average problem
-
In the first 10 overs of a cricket game, the run
rate was only 3.2. What should be the run rate
in the remaining 40 overs to reach the target of
282 runs?
Ans: 6.25
-
150.
Partnership
-
A and B invest in a business in the ratio 3 : 2. If
5% of the total profit goes to charity and A's
share is Rs. 855, the total profit is:
Ans: Rs. 1500
-
Faculty Team Prepared
Signatures
1.
Mrs.V.Geethanjali,AP/ECE
2.
Dr.P.Padmaloshani,
ASP/ECE
3.
Ms.K.Shenbagadevi, AP/ECE
HoD
